Digital vs. Electronic Signatures: The Technical Difference

The terms are often used interchangeably, but in the realm of document architecture, they represent entirely different technologies.

The Electronic Signature (e-Signature)

An electronic signature is a broad legal concept. Technically, it is often just a visual representation (a drawn PNG, or typed text) placed onto the document.

• Technical Mechanism: Modifying the PDF's visual layer to append an image or text block.
• Validation: Relies on the context of the transaction, audit trails, and intent.
• Tamper Evidence: None inherently. The PDF can be modified later without invalidating the visual signature.

The Digital Signature

A digital signature is a specific, cryptographic implementation of an electronic signature.

• Technical Mechanism: Uses Public Key Infrastructure (PKI). A hash of the document is encrypted with the signer's private key and embedded into the PDF structure (specifically in the `/ByteRange` and `/Contents` dictionary).
• Validation: PDF readers (like Adobe Acrobat) use the signer's public key certificate to decrypt the hash and verify it matches the current document hash.
• Tamper Evidence: High. If a single byte of the signed document content changes, the hashes will not match, and the PDF reader will display a "Signature Invalid" warning.

uSignPDF currently provides robust electronic signatures via local browser processing. If you need cryptographic digital signatures, you must use desktop software with access to your private key certificates.